1. Field of the Invention
The present invention relates generally to administration of medication. More specifically, the present invention relates to the administration of medication by a method and apparatus for facilitating inhalation of dry powder medicaments.
2. Related art
In the medical field, it is often desirable to administer various forms of medication to patients. Well known methods of introducing medication into the human body include the oral ingestion of capsules and tablets, intravenous injection through hypodermic needles, and numerous others. In one method, certain medications may be inhaled into a patient's respiratory tract and lungs through the nose or mouth. Certain of these medications, such as bronchodilators, corticosteroids, etc., for the treatment of asthma and other respiratory anomalies, may be aimed at the respiratory tract directly. Others are inhaled for purposes of systemic treatment, i.e. for treatment of any area of the body through absorption from the respiratory tract through the lung tissue, into the deep lungs, and into the bloodstream. Each of these medications comes in a variety of forms, including fluids, which are commonly administered as an aerosol vapor or mist, as well as solids. Inhalable solids typically take the form of fine, dry powders. Specialized devices, such as inhalers, are provided to assist the patient in directing these fine powder medications into the respiratory tract.
A variety of inhalers are known for the administration of dry powder medicaments. However, each of these inhalers suffers certain drawbacks. For example, U.S. Pat. No. 5,787,881 discloses an inhaler that is used with encapsulated dry powder medicaments. However, use of this device requires numerous steps and imposes a number of inconveniences on a user. For example, the medication capsules used with the device have an aperture formed therein prior to insertion into an opening in the inhaler. Therefore, there exists a danger that an amount of medication may be lost prior to or during insertion into the device. After insertion of the capsule, use of the device requires the additional step that a cover must be closed before the medication may be inhaled. Further inconveniences arise during periods of nonuse of the device. For example, because medication is not inserted into the device until just prior to use, the medication and the device may inadvertently become separated, and alone, each is useless. Furthermore, because the device is circular in shape, it is not as readily stored as a flatter device would be in locations such as wallet or pocket, for example.
The above inhaler and others which are known may be operated in a positive gas assisted manner, such as with a source of compressed air or other gas. These devices are inconvenient for a user in that the compressed gas source must be carried with the inhaler if medication is to be effectively administered. Also, these devices carry the additional danger that a pressurized container may become ruptured.
Propellant-free inhalers, which depend only on an inspiration by a user, are also known. One such device is disclosed in U.S. Pat. No. 5,575,280. This device houses in a storage chamber an amount of medication sufficient for administration of more than one dose. Just prior to each use, a notched wheel rotates to meter an amount of powder into a separate chamber for inhalation. However, if the medication does not properly fill such a notch, because of an air pocket, for example, an improper amount of medication may be administered following rotation of the wheel. This inaccuracy can potentially lead to ineffective treatment of an ailment, and thereby result in prolonged suffering by a patient.
Thus, there is a need in the art for an improved method and apparatus for inhalation of dry powder medicaments. What is needed is an inhaler having medication pre-stored therein, and which requires minimal steps by a user prior to use. Such a device would preferably come in a size and shape for portability and convenient storage by a user, and would be designed to avoid spillage or other events leading to inaccurate administration of medication, such that a proper dosage is administered each time such a device is used. The present invention, the description of which is fully set forth below, solves the need in the art for such improved methods and apparatus.